When I received this book (and the counterpart DbContext), I was a little disappointed at how short it is. But it's actually just very focused and concise, a rarity in most programming books. Well written, clear, and to the point with no fluff.
If you're new to EntityFramework, you still probably need to read the seminal Programming EntityFramework, but this is a very good companion covering an aspect of EF I'd like to use.